Column clamp



Patented Nov. 20, 1928.

UNITED: STATES CHARLES M. MAItKI-IAM, OF INDIANAPOLIS, INDIANA.

- COLUMN CLAMP.

Application filed July 27; 1925. Serial No. 46,247.

It is the object of my invention to produce a clamp which can be employed to hold firmly together hollow forms such as are used in the construction of reinforced concrete columns. A further object of my invention is to produce such a clamp which will comprise but few parts, which may be simply and economically manufactured, which is positive in its clamping action, and which may be easily released to permit the removal of the form from the column.

I accomplish the above objects by providing four bars pivotally connected together in pairs and adapted to surround a square or rectangular column for-m, extending horizontally across the faces thereof and projecting beyond such faces so that the free ends of one pair of bars cross'and extend beyond the free ends of the other pair; and I provide each bar with a dog adapted to bear against the intersecting bar and retain the clamp firmly in position about the column.

The accompanying drawing illustrates my invention: Fig. 1 is a perspective view of my column clamp in place on a. square columnform; Fig. 2 is a section on the line 22 of Fig. 3; and Fig. 3 is a plan showing details of construction.

A column-form of the type which my clamp is designed to hold together is composed of four side-members 10, which when placed together as illustrated in Fig. 1 form a hollow mold for a concrete column. The side members 10 are held in place by means of my improved clamp which comprises two pairs of bars 11 and 12 the bars of each pair being pivotally connected, the four bars being adapted to surround the column form with the free ends of one pair of bars crossing the free ends of the other pair.

Each of the bars is provided with a sliding dog 13 having an inwardly projecting finger 14, the fingers 1 1 on those dogs associated with one pair of bars being adapted respectively to engage the edges of the other pair of bars. Preferably, each dog is also provided with a guide 15 adapted to overlie the bar against which the finger 14 of such a dog bears.

Each dog 13 is provided with a hole for the reception of one of the bars 11 and 12, such hole extending diagonally through the dogs as is evident from Fig. 3. The diagonally extending sides of such hole intersect the sides of the dog to form acute angle corners 13 adapted to grip the edges of the bar when pressure is applied to the finger 14. Thus,

the ,dog 13 tilts slightly to permit its associated bar to be drawn through it in a direction to tighten the clamp, but tilts back again to'prevent movement in the reverse direction.

Means for tightening the clamp about the column. comprises a member 16 adapted to be placedon the proj ectingend of any of the bars 11 or 12. Pivotally mounted in such sliding member 16 is a pawl 17, on the outer end of which is pivotally mounted a lever. 18. The pawl 17 is provided with teeth .19 which are located on a surface eccentric to the pivotal mounting of such pawl so that when the pawl tends to rotate in a clockwise direction (Fig. 3) the teeth 19 will engage the edge of the bar with which the member 16 is associated and prevent movement of such member along the bar. The lever 18 isprovided with a project-ing end which is adapted to bear against the dog 13 at a point between the finger 14 of such dog and the bar on which the dog is mounted.

To tighten the column clamp about the column form, the member 16 is placed on the projecting end of one of the bars, here shown as one of the bars 11, and is moved along such bar until the projecting end of the lever 18 engages the dog 13. If the lever 18 is now drawn in a direction away from the 001- P umn, the teeth 19 of the pawl 17 will be forced firmly into engagement with the bar 11 to clamp the member 16 to such bar. Continued outward movement of the lever 18 draws the bar 11 through the dog 13 associated with it and tightens the clamp upon the column form. The pressure of the projecting end of the lever-.18 upon the dog 13 tends to hold the corners 13 firmly in contact with the edges of the bar 11 so that upon release of the lever 18 the dog will immediately grip the bar 11 and prevent it from creeping in a direction to loosen the clamp. When it is desired to loosen the clamp, the outer end of each of the dogs 13 may be forced backward by using the end of the lever 18, such lever being bent for the purpose as is clear from the dotted line shown in Fig. 3.

To prevent the dogs 13 from sliding ofl their associated rods and becoming lost, I

provide each of the rods 11 and 12 with a cross.

I have described my column clamp as applied to a square or rectangular column form, but it will be obvious that it is not limited to use with four-sided molds.

I claim as my invention:

1. A clamp for clamping together hollow polygonal column forms, comprising a bar adapted to extend across each outer face of such form, said bars being arranged to cross in pairs at corners of such form, a locking dog on each bar having a portion rigid with the remainder of the dog for engaging the intersecting bar, each of said dogs being adapted to grip its 'own bar by outward presvided with an extended finger adapted to engage the intersecting bar, whereby outward pressure of such intersecting bar tends to tilt said dog to cause it to grip its associated bar and prevent loosening of the clamp and clamp-tightening means adapted to draw each of said bars through the dog thereon.

3. A column clamp as set forth in claim 1 with the addition that said tightening means is arranged to act between a bar and the dog thereon.

4. A column clamp as set forth in claim 2 with the addition that said tightening means is arranged to act between a bar and the dog thereon.

5. A column clamp as set forth in claim 1 with the addition that said tightening means comprises a member slidable on each of said bars, a pawl movably mounted in said memher to lock said bar and said member together, and an operating lever fulcrumed on said pawl and arranged when operated to tighten the clamp to cause said pawl to lock said member and bar together.

In witness whereof, I have hereunto set my hand at Indianapolis, Indiana, this 18th day of July, A. D. one thousand nine hundred and twenty-five.

CHARLES M. MARKHAM. 

